diff --git a/src/apps.js b/src/apps.js
index 62149af5d..96b64ce60 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -983,8 +983,7 @@ function setDebugMode(appId, debugMode, auditSource, callback) {
 
 function setMailbox(appId, mailboxName, auditSource, callback) {
     assert.strictEqual(typeof appId, 'string');
-    assert(!mailboxName || typeof mailboxName === 'string');
-    assert.strictEqual(typeof memoryLimit, 'number');
+    assert(mailboxName === null || typeof mailboxName === 'string');
     assert.strictEqual(typeof auditSource, 'object');
     assert.strictEqual(typeof callback, 'function');
 
@@ -998,7 +997,7 @@ function setMailbox(appId, mailboxName, auditSource, callback) {
             mailboxName = mailboxNameForLocation(app.location, app.manifest);
         }
 
-        scheduleTask(appId, {}, { installationState: exports.ISTATE_PENDING_CREATE, mailboxName: mailboxName }, function (error, result) {
+        scheduleTask(appId, {}, { installationState: exports.ISTATE_PENDING_CREATE_CONTAINER, mailboxName: mailboxName }, function (error, result) {
             if (error) return callback(error);
 
             eventlog.add(eventlog.ACTION_APP_CONFIGURE, auditSource, { appId: appId, app: app, mailboxName: mailboxName, taskId: result.taskId });
@@ -1132,6 +1131,9 @@ function setLocation(appId, data, auditSource, callback) {
             values.alternateDomains = data.alternateDomains;
         }
 
+        // move the mailbox name to match the new location
+        if (app.mailboxName.endsWith('.app')) values.mailboxName = mailboxNameForLocation(values.location, app.manifest);
+
         domains.get(values.domain, function (error, domainObject) {
             if (error && error.reason === DomainsError.NOT_FOUND) return callback(new AppsError(AppsError.NOT_FOUND, 'No such domain'));
             if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, 'Could not get domain info:' + error.message));
diff --git a/src/apptask.js b/src/apptask.js
index caca15b94..939faae48 100644
--- a/src/apptask.js
+++ b/src/apptask.js
@@ -617,6 +617,10 @@ function create(app, progressCallback, callback) {
         stopApp.bind(null, app, progressCallback),
         deleteContainers.bind(null, app, { managedOnly: true }),
 
+        // FIXME: re-setup addons only because sendmail addon to re-inject env vars on mailboxName change
+        progressCallback.bind(null, { percent: 30, message: 'Setting up addons' }),
+        addons.setupAddons.bind(null, app, app.manifest.addons),
+
         progressCallback.bind(null, { percent: 60, message: 'Creating container' }),
         createContainer.bind(null, app),
 
diff --git a/src/routes/test/apps-test.js b/src/routes/test/apps-test.js
index 5b391b235..5720ab27f 100644
--- a/src/routes/test/apps-test.js
+++ b/src/routes/test/apps-test.js
@@ -478,6 +478,7 @@ describe('App API', function () {
                     expect(res.statusCode).to.equal(200);
                     expect(res.body.id).to.eql(APP_ID);
                     expect(res.body.installationState).to.be.ok();
+                    expect(res.body.mailboxName).to.be(APP_LOCATION + '.app');
                     done();
                 });
         });
@@ -1084,10 +1085,12 @@ describe('App API', function () {
             waitForTask(taskId, done);
         });
 
-        it('did change env vars', function (done) {
+        it('did change location', function (done) {
             apps.get(APP_ID, function (error, app) {
                 if (error) return done(error);
 
+                expect(app.mailboxName).to.be(APP_LOCATION_NEW + '.app'); // must follow location change
+
                 docker.getContainer(app.containerId).inspect(function (error, data) {
                     expect(error).to.not.be.ok();
                     expect(data.Config.Env).to.contain('CLOUDRON_APP_ORIGIN=https://' + APP_LOCATION_NEW + '.' + DOMAIN_0.domain);
@@ -1275,6 +1278,82 @@ describe('App API', function () {
         });
     });
 
+    describe('configure mailbox', function () {
+        it('fails with missing mailbox', function (done) {
+            superagent.post(SERVER_URL + '/api/v1/apps/' + APP_ID + '/configure/mailbox')
+                .query({ access_token: token })
+                .end(function (err, res) {
+                    expect(res.statusCode).to.equal(400);
+                    done();
+                });
+        });
+
+        it('fails with bad mailbox', function (done) {
+            superagent.post(SERVER_URL + '/api/v1/apps/' + APP_ID + '/configure/mailbox')
+                .query({ access_token: token })
+                .send({ mailbox: 'genos@cloudron.io' })
+                .end(function (err, res) {
+                    expect(res.statusCode).to.equal(400);
+                    done();
+                });
+        });
+
+        it('can set mailbox', function (done) {
+            superagent.post(SERVER_URL + '/api/v1/apps/' + APP_ID + '/configure/mailbox')
+                .query({ access_token: token })
+                .send({ mailboxName: 'genos' })
+                .end(function (err, res) {
+                    expect(res.statusCode).to.equal(202);
+                    taskId = res.body.taskId;
+                    done();
+                });
+        });
+
+        it('wait for task', function (done) {
+            waitForTask(taskId, done);
+        });
+
+        it('did set mailbox', function (done) {
+            apps.get(APP_ID, function (error, app) {
+                if (error) return done(error);
+
+                docker.getContainer(app.containerId).inspect(function (error, data) {
+                    expect(error).to.not.be.ok();
+
+                    expect(data.Config.Env).to.contain('CLOUDRON_MAIL_FROM=genos@' + app.domain);
+                    done();
+                });
+            });
+        });
+
+        it('can reset mailbox', function (done) {
+            superagent.post(SERVER_URL + '/api/v1/apps/' + APP_ID + '/configure/mailbox')
+                .query({ access_token: token })
+                .send({ mailboxName: null })
+                .end(function (err, res) {
+                    expect(res.statusCode).to.equal(202);
+                    taskId = res.body.taskId;
+                    done();
+                });
+        });
+
+        it('wait for task', function (done) {
+            waitForTask(taskId, done);
+        });
+
+        it('did reset mailbox', function (done) {
+            apps.get(APP_ID, function (error, app) {
+                if (error) return done(error);
+
+                docker.getContainer(app.containerId).inspect(function (error, data) {
+                    expect(error).to.not.be.ok();
+                    expect(data.Config.Env).to.not.contain('CLOUDRON_MAIL_FROM=' + app.location + '@' + app.domain + '.app');
+                    done();
+                });
+            });
+        });
+    });
+
     describe('start/stop', function () {
         it('non admin cannot stop app', function (done) {
             superagent.post(SERVER_URL + '/api/v1/apps/' + APP_ID + '/stop')